1. Field of the Invention
The present invention relates to a method and apparatus for managing signaling links in a signaling link set.
2. Background of the Related Art
A signaling system No. 7 (SS7) is a common channel signaling system that transmits a plurality of voice signals through separate channels by separating a talking path from a signaling path completely. An SS7 network, as illustrated in FIG. 1, includes a plurality of signaling points including a signaling end point (SEP) that handles outgoing or incoming of signal messages, a signaling transfer point (STP) that transmits signal messages, and a signaling link (SL) that is a logical information transmission line connecting the signaling points.
A set of signaling links (SL) is designated as a signaling link set (LS) and an SEP is classified into an originating point (OP) generating signal messages and a destination point (DP) that is a destination of signal messages.
In a signaling system No. 7 network, one signaling point may make up one signaling link set with an adjacent signaling point. At this time, one signaling link set may accommodate 16 signaling links at most and the signaling link set may only accommodate signaling links having the same kind of data link format.
Referring to FIG. 2, the protocol structure of each signaling point in the SS7 network includes a message transfer part (MTP) level 1 to MTP level 3 performing a signaling data link function and a signal message transferring and processing function; and an MTP user part level 4, an user part using functions provided by the MTP such as a signaling connection control part (SCCP), a telephone user part (TUP), an integrated services digital network (ISDN) user part (ISUP) and etc. The MTP performs a function of transferring signal messages of the MTP user part through signaling links and is classified into level 1 designating physical, electrical and mechanical characteristics of data links; level 2 performing functions of transferring signal messages, controlling flow of signal messages, detecting errors and monitoring signaling links; and level 3 which performs signal message processing and managing functions.
The MTP level 3 includes a signal message processing part performing a signaling traffic transferring function and an user part message distributing function. MTP level 3 also includes a signaling network managing part which efficiently uses every component of the signaling network (such as signaling links, signaling link sets and signaling points) to transfer signal messages with high reliability, maintain stable relationship between components of the signaling network, and perform signaling network configuration managing functions.
In the SS7 network, if signal messages to be transferred exist at a signaling point, the signaling point transfers the signal messages to an adjacent signaling point through available signaling links in a signaling link set, which connects the signaling point and the adjacent signaling point. The adjacent signaling point, which receives the signal messages through the available signaling link in the signaling link set, transfers the signal messages to another adjacent signaling point through available signaling links in another signaling link set. Until the signal messages are transferred to a destination point, the signal messages are transferred in the above-mentioned way.
In the end, the signal messages are transferred to the destination point. The signal message transfer is performed at the signal message processing part of the MTP level 3 using header information included in each signal message which is designated as a routing label. More specifically, the signal message processing part transfers the signal messages to the destination point using the routing label which includes a signaling link selection (SLS), an originating point code (OPC) and a destination point code (DPC) of the signal messages, as illustrated in FIG. 3.
In the SS7 network, if a plurality of signaling links are available in a signaling link set connecting signaling points, signal messages may be transferred through the available signaling links. Accordingly, if data links of signaling links transferring the signal messages are different, a transfer order of the signal messages may not be assured at the destination point of the signal messages. Thus, it is impossible for a signaling link set of the SS7 network to accommodate data links having different signal message transfer methods and different signal message transfer quantities (e.g., different MTP level 1 and level 2) together.
The SS7 network is generally used for call set up and call release in a signaling network for mobile communication. In order to perform call set up and call release in the SS7 network, each signaling point transfers and receives signal messages according to a predetermined scenario. If different data links are accommodated by one signaling link set, a transfer order of signal messages may not be assured. Thus, it is possible to implement different data links in a signaling link set in terms of hardware technology but it is impossible to simultaneously use signaling links having different data link formats in one signaling link set in terms of transferring short messages.
As information to be transferred between signaling points in the SS7 network increases due to the advent of next generation mobile communication system such as IMT-2000, it is preferable to connect each signaling point with data links that have broader bandwidth. Nonetheless, it is impossible for one signaling link set of the SS7 network in the related art to accommodate different data links having different bandwidths. Consequently, new data links having higher bandwidth must be configured after removing every data link used in the signaling link set. The SS7 network of the related art thus has problems in that natural development of signaling networks may not be achieved. Moreover, configuring the developed signaling networks is not economical because data links used prior to the development of signaling networks may not be used.
Consider for example, the case where a signaling link set includes data links of 64 kbps. If an E1 data link of 2.048 Mbps is required due to a request for processing more signal messages, all signaling links of the signaling link set should be replaced in order to add the data link of 2.048 Mbps, without accommodating the data links of 64 kbps. Thus, there is a problem in the related art that great expenses are needed for development of the signaling network.